Method and system for fast on-line electro-optical detection of wafer defects

ABSTRACT

A method and system for fast on-line electro-optical detection of wafer defects featuring illuminating with a short light pulse from a repetitively pulsed laser, a field of view of an electro-optical camera system having microscopy optics, and imaging a moving wafer, on to a focal plane assembly optically forming a surface of photo-detectors at the focal plane of the optical imaging system, formed from six detector ensembles, each ensemble including an array of four two-dimensional CCD matrix photo-detectors, whereby each two-dimensional CCD matrix photo-detector produces an electronic image of a large matrix of two million pixels, such that the simultaneously created images from the different CCD matrix detectors are processed in parallel using conventional image processing techniques, for comparing the imaged field of view with another field of view serving as a reference, in order to find differences in corresponding pixels, indicative of the presence of a wafer die defect.

The instant application is a continuation application of U.S.application Ser. No. 10/173,040 abandoned, filed Jun. 18, 2002abandoned, which is a continuation application of U.S. application Ser.No. 09/343,198 abandoned, filed Jun. 30, 1999.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to methods and systems forelectro-optically detecting fabrication defects, which are random innature, in semiconductor patterned structures such as a semiconductorwafer featuring integrated circuit dies or chips. In particular, thepresent invention relates to a method and system for fast on-lineelectro-optical detection of wafer defects by illuminating with a shortlight pulse from a pulsed laser, a field of view of an electro-opticalcamera system having microscopy optics, and imaging, a moving wafer, onto a focal plane assembly (FPA) optically forming a surface ofphoto-detectors at the focal plane of an optical imaging system, formedfrom several detector ensembles, each detector ensemble including anarray of several two-dimensional matrix photo-detectors, where eachtwo-dimensional matrix photo-detector produces an electronic imagefeaturing a matrix of picture elements (pixels), such that thesimultaneously created images from the different matrix photo-detectorsare processed in parallel using conventional image processingtechniques, for comparing the imaged field of view with another field ofview serving as a reference, in order to find differences incorresponding pixels, indicative of the presence of a wafer die defect.

Hereinafter, the term ‘wafer’ refers to, and is generally considered tofeature individual patterned structures, known as ‘semiconductor waferdice’, ‘wafer dice’, or wafer chips’. Current semiconductor technologyinvolves the physical division of a single wafer into identical dies forthe manufacture of integrated circuit chips, such that each die becomesan individual integrated circuit chip having a specific pattern, such asa memory chip or a microprocessor chip, for example. The type of chipproduced from a given die is not relevant to the method or system of thepresent invention.

Hereinafter, the term ‘field of view’ refers to that part or segment of,a wafer, in general, and a wafer die, in particular, illuminated by apulsed laser and imaged by the electro-optical camera system inspectionoptics in conjunction with the FPA. Accordingly, an entire single waferdie, and therefore, an entire single wafer featuring a plurality ofwafer dies, is inspected by sequential imaging of a plurality orsequence of fields of view. The field of view can be considered as theinspection system electro-optical imaging footprint on the wafer orwafer die. Successive fields of view created while the wafer is movingin one direction are referred to as a ‘strip’ of fields of view. Pixelsare referred to with respect to forming an image of a field of view bythe electro-optical inspection system. As a reference dimension, generalorder of magnitude of the size of a typically square wafer die within awafer is 1 centimeter by 1 centimeter, or 10⁴ microns by 10⁴ microns.

Hereinafter, detection of a ‘wafer defect’ refers to the detection ofthe presence of an irregularity or difference in the comparison of likepatterns of wafer dies or like patterns of fields of view. Currentmethods and systems of defect detection on wafers are usually based onthe analysis of comparing signals obtained from a number of adjacentwafer dies or fields of view, featuring a like pattern. Defects producedduring wafer fabrication are assumed to be random in nature. Therefore,defect detection is based on a statistical approach, whereby theprobability that a random defect will exist at the same location withinadjacent wafer dies is very low. Hence, defect detection is commonlybased on identifying irregularities through the use of the well knownmethod of die-to-die comparison. A given inspection system is programmedto inspect the pattern of a wafer die or field of view, typicallyreferred to as the inspected pattern, and then compares it to theidentical pattern of a second wafer die or field of view on the samewafer, serving as the reference pattern, to detect any patternirregularity or difference which would indicate the possible presence ofa wafer defect. A second comparison between the previously designatedinspected pattern and the like pattern of a third wafer die or field ofview is performed, in order to confirm the presence of a defect and toidentify the wafer die or field of view containing the defect. In thesecond comparison, the first wafer die or field of view is considered areference and the third wafer die or field of view is considered asinspected.

Fabrication of semiconductor wafers is highly complex and veryexpensive, and the miniature integrated circuit patterns ofsemiconductor wafers are highly sensitive to process induced defects,foreign material particulates, and equipment malfunctions. Costs relatedto the presence of wafer defects are multiplied several fold when goingfrom development stages to mass production stages. Therefore, thesemiconductor industry critically depends on a very fast ramp-up ofwafer yield at the initial phase of production, and then achieving andcontrolling a continuous high yield during volume production.

Critical dimensions of integrated circuits on wafers are continuouslydecreasing, approaching 0.1 micron. Therefore, advanced semiconductorwafers are vulnerable to smaller sized defects than are currentlydetected. Current methods of monitoring wafer yield involve opticallyinspecting, in-process, wafers for defects and establishing a feedbackloop, with appropriate parametric process control, between thefabrication process and the manufactured wafers. To detect smaller sizeddefects, optical inspection systems need to have higher resolution viascanning wafers using smaller pixel sizes. Scanning a given sized waferusing pixel sizes smaller causes an increase in per wafer inspectiontime, resulting in decreased wafer throughput, and decreased statisticalsample sizes of the number of inspected wafers. Conversely, attemptingto increase wafer inspection throughput by using current optical systempixel sizes results in reducing the effectiveness, i.e., resolution, ofdetecting wafer defects.

In addition to decreasing critical dimensions of wafers, thesemiconductor industry is in the process of converting frommanufacturing 8-inch wafers to 12-inch wafers. Larger, 12-inch wafershave more than twice the surface area compared to 8-inch wafers, andtherefore, for a given inspection system, inspection time per 12-inchwafer is expected to be twice as long as that per 8-inch wafer.Fabricating 12-inch wafers is significantly more expensive thanfabricating 8-inch wafers. In particular, costs of raw materials of12-inch wafers are higher than those of 8-inch wafers. One result ofwafer size conversion, is that cost effective productivity of futurewafer manufacturing will depend critically upon increasing speed andthroughput of wafer inspection systems.

Automated wafer inspection systems are used for quality control andquality assurance of wafer fabrication processes, equipment, andproducts. Such systems are used for monitoring purposes and are notdirectly involved in the fabrication process. As for any principlecomponent of an overall manufacturing system, it is important that awafer inspection method, and system of implementation, be cost effectiverelative to the overall costs of manufacturing semiconductor wafers.

There is thus a need to inspect semiconductor wafers for wafer diedefects, for wafers featuring larger sizes and smaller criticaldimensions, at higher throughput than is currently available, and in acost effective manner.

Automated optical wafer inspection systems were introduced in the 1980'swhen advances in electro-optics, computer platforms with associatedsoftware and image processing made possible the changeover from manualto automated wafer inspection. However, inspection speed, andconsequently, wafer throughput of these systems became technologylimited and didn't keep up with increasingly stringent productionrequirements, i.e., fabricating integrated circuit chips from wafers ofincreasing size and decreasing critical dimensions. Current waferinspection systems typically use continuous illumination, and create atwo dimensional image of a wafer segment, by scanning the wafer in twodimensions. This is a relatively slow process, and as a result, quantityof on-line inspection data acquired during a manufacturing process issmall, generating a relatively small statistical sample of inspectedwafers, translating to relatively long times required to detect waferfabrication problems. Slow systems of on-line defect detection result inconsiderable wafer scrap, low wafer production yields, and overall longturn-around-times for pin-pointing fabrication processing steps and/orequipment causing wafer defects.

A notable limitation of current methods and systems of wafer defectdetection relates to registration of pixel positions in wafer images.Before wafer defects can be detected by standard techniques of comparingdifferences in pixel intensities of an image of a targeted or inspectedwafer die to pixel intensities of an image of a reference wafer die, thepixel positions of the images of the inspected and reference wafer dieneed to be registered. Due to typical mechanical inaccuracies duringmovement of a wafer held on a translation stage, velocity of a waferbeneath a wafer inspection camera system is not constant. As a result ofthis, image pixel positions in the fields of a detector are distortedand may not be as initially programmed. Therefore, a best fittwo-dimensional translation pixel registration correction is performed.

Prior art methods and systems of wafer defect detection, featuring acombination of continuous wafer illumination and acquiring a twodimensional image by either scanning a wafer in two dimensions using alaser flying spot scanner as taught in U.S. Pat. No. 5,699,447, issuedto Alumot et al., or scanning a wafer in one dimension using a lineararray of photo detectors as taught in U.S. Pat. No. 4,247,203, issued toLevy et al., require a registration correction for all pixels or allpixel lines. These methods limit system speed, i.e. inspectionthroughput, and require substantial electronic hardware. Moreover, theyresult in residual misregistration, since no correction procedure isaccurate for all pixels in an image. Residual misregistrationsignificantly reduces system defect detection sensitivity. For a waferinspection method or system in which all focal plane assembly pixels inany given field can be considered one unit, generated simultaneously,there is no need for image pixel registration within a field of view ofa focal plane assembly. Therefore, only a single two dimensionalalignment correction between the inspected field of view and theequivalent zone in a reference field of view is needed and a singlealignment correction will be correct over the entire focal planeassembly field of view. Such a procedure results in negligible residualmisregistration, enabling improved defect detection sensitivity. Thereis thus a need for a method or system of on-line electro-opticaldetection of wafer die defects which includes minimization of residualmisregistration of image pixel positions.

An apparatus for wafer inspection is disclosed in U.S. Pat. Nos.4,247,203, and 4,347,001, both issued to Levy at al. The apparatusdescribed in those patents locates defects or faults in photomasks bysimultaneously comparing patterns of adjacent dies on the photomask andlocating differences. Using two different imaging channels, equivalentfields of view of each die are simultaneously imaged, and the images areelectronically digitized by two linear diode array photo-detectors, eachcontaining 512 pixels. A two dimensional image of a selected field ofview of each die is generated by mechanically moving the object underinspection in one direction, and electronically scanning the arrayelements in the orthogonal direction. During the detector exposure time,the photomask can not be moved a distance of more than one pixel or theimage becomes smeared. Therefore, the time to scan and inspect thephotomask is very long. Since the photomask is moved continuously whilethe two dimensional images are generated, it is necessary that thephotomask move without jitter and accelerations. This motion restrictionrequires a very massive and accurate air-bearing stage for holding andmoving the photomask, which is costly. In addition, the wafer inspectionapparatus of Levy et al. is capable of detecting 2.5 micron defects with95% probability of detection on photomasks. For critical dimensions ofcurrent semiconductor, integrated circuits approaching 0.1 micron, thismeans that the inspecting pixel must be of similar size magnitude. Sinceinspection speed increases inversely with squared pixel size, theapparatus of Levy et al. would slow down by more than two orders ofmagnitude. Furthermore, it becomes impractical to implement a motionstage capable of meeting the required mechanical accuracies.

Wafer inspection has also been implemented using a single imaging anddetection channel, based on a solid state camera using a two dimensionalCCD matrix photo-detector, such as described in ‘Machine Vision andApplications’, (1998) 1: 205-221, by IBM scientists Byron E. Dom et al.A wafer inspection system designated as P300 is described for inspectingpatterned wafers having a repetitive pattern of cells within each die,such as in semiconductor wafers for memory devices. The system capturesan image field of view having 480 by 512 pixels. The image processingalgorithms assume a known horizontal cell periodicity, R, in the image,and analyzes each pixel in the image by comparing it with two pixels,one pattern repetition period, R, away in either horizontal direction.Such a comparison of like cells within a single image is called acell-to-cell comparison. The pixel under test is compared with periodicneighbors on both sides to resolve the ambiguity that would exist if itwere compared with only a single pixel. While this system is capable ofsimultaneously capturing a two dimensional image of the object undertest, it is very slow in inspecting an entire wafer. Millions of imagefields are needed to image an entire wafer, and since the system usescontinuous illumination, such as is used with standard microscopes, thewafer must be moved, under the inspection camera, from field to fieldand stopped during the image exposure to avoid image smear. To reachanother field, the mechanical motion stage carrying the wafer mustaccelerate, and than decelerate to a stop at a new position. Each suchmotion takes a relatively long time and therefore inspecting a wafertypically takes many hours.

There is thus a need for, and it would be useful to have, a fast on-linemethod and a system to inspect semiconductor wafers for wafer diedefects, for wafers featuring larger sizes and smaller criticaldimensions, at higher throughput than is currently available, whileproviding high levels of image resolution of water dies, in a costeffective manner.

SUMMARY OF THE INVENTION

The present invention relates to a method and system for fast on-lineelectro-optical detection of wafer die defects by illuminating with ashort light pulse from a pulsed laser, a field of view of anelectro-optical camera system having microscopy optics, and imaging amoving wafer, on to a focal plane assembly optically forming a surfaceof photo-detectors at the focal plane of an optical imaging system,formed from several, for example six detector ensembles, each detectorensemble including an array of several, for example, four,two-dimensional charge coupled device (CCD) matrix photo-detectors,whereby each two-dimensional CCD matrix photo-detector produces anelectronic image containing a large matrix of, for example, two million,pixels, such that the simultaneously created images from the differentCCD matrix detectors are processed in parallel using conventional imageprocessing techniques, for comparing the imaged field of view withanother field of view serving as a reference, in order to finddifferences in corresponding pixels, indicative of the presence of awafer die defect.

In particular, the method and system of the present invention enablecapturing high pixel density, large field of view images of a wafer die,on-the-fly, without stopping movement of the wafer. High accuracy ofwafer motion speed is not needed, and a relatively simple inexpensivemechanical stage for moving the wafer can be used. The continuouslymoving wafer is illuminated with a laser pulse of such short duration,for example, ten nanoseconds, significantly shorter than the image pixeldwell time, that there is effectively no image smear during the wafermotion. During the time interval of the laser pulse, a wafer die imagemoves less than a tenth of a pixel. The laser pulse has sufficientenergy and brightness to impart the necessary illumination to theinspected field of view required for creating an image of the inspectedwafer die. In addition, as a result of the method and system featuringoptical coupling of the separate CCD matrix photo-detectors via thedetector ensembles and the focal plane assembly, processing time of anentire array of for example twenty-four CCD matrix photo-detectors,having imaging capacity of 48 megapixels, is equivalent to processingtime of a single CCD matrix photo-detector of the order of {fraction(1/30)} of a second, since the processing of all the photo-detectors isprocessed in parallel. Consequently, parallel processing of the entirefocal plane assembly including twenty-four CCD matrix photo-detectorsprovides an overall pixel processing data rate of nearly 1.5 gigapixelsper second. Furthermore, the overall wafer inspection system operatesessentially at 100% efficiency) whereby, the laser pulse rate of 30pulses per second is synchronized with the frame speed of 30 frames persecond of each CCD matrix photo-detector, and the wafer is moved at alinear speed such that the distance between successive fields of view iscovered in {fraction (1/30)} of a second.

The method and system of the present invention provide significantimprovements over currently used methods and systems for electro-opticalinspection and detection of wafer defects, in the semiconductor waferfabrication industry, including providing high resolution large field ofview wafer die images at very high wafer inspection throughput, andrequiring less electronic and system hardware. Moreover, as a directresult of using an array of several CCD matrix photo-detectors foracquiring a high pixel density image of a wafer die illuminated by asingle light pulse, the method and system of the present inventionprevents misregistration of pixel positions in the wafer die images,enabling enhanced defect detection sensitivity. Such a method and systemof wafer defect detection results in faster, more efficient, and costeffective, feedback control of wafer fabrication processes.

Thus, according to the present invention, there is provided a method forelectro-optically inspecting a patterned semiconductor wafer of dies fora defect, the method comprising the steps of: (a) moving the patternedwafer along an inspection path; (b) providing a repetitively pulsedlaser illuminating source; (c) sequentially illuminating each of aplurality of fields of view in each of a plurality of the wafer dies byusing the pulsed laser illuminating source; (d) sequentially acquiringan image of the each of the plurality of the sequentially illuminatedfields of view in each of a plurality of the wafer dies by using anelectro-optical camera including at least two two-dimensional matrixphoto-detectors, the at least two two-dimensional matrix photo-detectorssimultaneously acquiring images of each of the plurality of thesequentially illuminated fields of view in each of a plurality of thewafer dies; and (e) detecting a wafer defect by comparing thesequentially acquired images of each of the plurality of thesequentially illuminated fields of view in each of a plurality of thewafer dies using a die-to-die comparison method.

According to still further features in the described preferredembodiments, the repetitively pulsed laser is a Q switched Nd:YAG laser.

According to still further features in the described preferredembodiments, the Q switched Nd:YAG laser is optically pumped by lightemitting diodes.

According to still further features in the described preferredembodiments, the electro-optical camera further includes a non-linearoptical crystal functioning as a second harmonic generating crystal,placed in a laser beam light path of the repetitively pulsed laserillumination source, the non-linear optical crystal halving wavelengthsof the laser beam light generated by the repetitively pulsed laser.

According to the present invention, there is provided a system forelectro-optically inspecting a patterned semiconductor wafer of dies fora defect, the system comprising: (a) a mechanism for providing movementof the patterned wafer along an inspection path; (b) a repetitivelypulsed laser illumination source for illuminating the patterned wafer;(c) an electro-optical camera including at least two two-dimensionalmatrix photo-detectors for sequentially acquiring an image of each of aplurality of sequentially illuminated fields of view in each of aplurality of the wafer dies, the at least two two-dimensional matrixphoto-detectors operate with a mechanism for simultaneous acquisition ofimages of each of the plurality of the sequentially illuminated fieldsof view in each of a plurality of the wafer dies; and (d) an imageprocessing mechanism for processing the sequentially acquired images ofeach of the plurality of the illuminated fields of view in each of aplurality of the wafer dies and detecting a wafer defect by comparingthe sequentially acquired images using a die-to-die comparison method.

According to the present invention, there is provided an electro-opticalcamera for inspecting a patterned semiconductor wafer of dies for adefect, comprising a focal plane assembly including at least onedetector ensemble, the detector ensemble includes an array of at leasttwo two-dimensional matrix photo-detectors operating with a mechanismfor simultaneous acquisition of images of each of a plurality ofilluminated fields of view in each of a plurality of the wafer dies.

Implementation of the method and system of the present inventioninvolves performing or completing tasks or steps manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of a given wafer inspection system,several steps of the present invention could be implemented by hardwareor by software on any operating system of any firmware or a combinationthereof. For example, as hardware, indicated steps of the inventioncould be implemented as a chip or a circuit. As software, indicatedsteps of the invention could be implemented as a plurality of softwareinstructions being executed by a computer using any suitable operatingsystem. In any case, indicated steps of the method of the inventioncould be described as being performed by a data processor, such as acomputing platform for executing a plurality of instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1A and FIG. 1B is a flow diagram of a preferred embodiment of themethod for fast on-line electro-optical detection of wafer defects, inaccordance with the present invention;

FIG. 2 is a schematic diagram illustrating an exemplary preferredembodiment of the system for fast on-line electro-optical detection ofwafer defects, in accordance with the present invention;

FIG. 3A is a schematic diagram illustrating a top view of a CCD matrixphoto-detector, in accordance with the present invention;

FIG. 3B is a schematic diagram illustrating a side view of a CCD matrixphoto-detector, in accordance with the present invention;

FIG. 4A is a schematic diagram illustrating a close-up side view of adetector ensemble, including CCD matrix photo-detectors, and prisms, inaccordance with the present invention;

FIG. 4B is a schematic diagram illustrating another close-up side viewof a detector ensemble, including CCD matrix photo-detectors, andprisms, in accordance with the present invention;

FIG. 4C is a schematic diagram illustrating a close-up view of a surfaceof a glass prism, including zones of highly reflective coating, as partof the detector ensemble shown in FIGS. 4A-4B, in accordance with thepresent invention;

FIG. 4D is a schematic diagram illustrating a close-up front opticalview, of the detector ensemble shown in FIGS. 4A-4C, showing theappearance of an optically continuous surface of photo-detectors,featuring a plurality of CCD matrix photo-detectors, in accordance withthe present invention;

FIG. 5A is a schematic diagram illustrating a close-up view of the focalplane assembly, including beam splitting prisms and detector ensembles,in accordance with the present invention;

FIG. 5B is a schematic diagram illustrating an optically formedcontinuous surface of photo-detectors at the focal plane formed by thedetector ensembles of the focal plane assembly and including several CCDmatrix photo-detectors, in accordance with the present invention; and

FIG. 6 is a schematic diagram illustrating a close-up view of the imageacquisition process featuring wafer dies, where each wafer die issequentially inspected by imaging a plurality or strips of fields ofview, one field of view at a time, in accordance with the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a method and system for fast on-lineelectro-optical detection of wafer defects.

The method and system for fast on-line electro-optical detection ofwafer defects of the present invention introduces the unique combinationof a new imaging system featuring an optically formed surface ofphoto-detectors at the focal plane formed from an array of severaltwo-dimensional matrix photo-detectors for acquiring a high resolution,high pixel density, large field of view image of a wafer die,synchronized with an illumination system featuring illumination of thewafer die by a short light pulse from a repetitively pulsed laser. Thelaser light pulse duration is significantly shorter than the image pixeldwell time, where the pixel dwell time refers to the time a point on thewafer is imaged by a detector pixel while the wafer is moving, and thelaser light pulse rate is synchronized with the frame speed of theindividual matrix photo-detectors.

Steps of operation of the method, and components of the system of thepresent invention are better understood with reference to the drawingsand the accompanying description. It is to be noted that illustrationsof the present invention shown here are for illustrative purposes onlyand are not meant to be limiting.

Referring now to the drawings, FIG. 1 is a flow diagram of a preferredembodiment of a method for fast electro-optical on-line detection ofwafer defects. In FIG. 1, each generally applicable, principle step ofthe method of the present invention is numbered and enclosed inside aframe. Sub-steps representing further of an indicated principle step ofthe method are indicated by a letter in parentheses. FIGS. 2 through 6are schematic diagrams illustrating exemplary preferred embodiments ofthe system, and of system components, for implementing the method forfast on-line electro-optical detection of wafer defects of the presentinvention. System components shown in FIGS. 2 through 6 corresponding tothe method of FIG. 1 are referred to in the description of FIG. 1.Details and specific examples of system components of FIGS. 2 through 6are provided throughout the following description. Terminology andreferences appearing in the following description of FIG. 1 areconsistent with those shown in FIGS. 2-6.

In Step 1 of the method, a patterned semiconductor wafer 12 featuring aplurality of wafer dies 14, is placed and aligned on a continuous movingXY translation stage 16. This is shown in system 10 of FIG. 2, which isa schematic diagram illustrating an exemplary preferred embodiment ofthe system for fast on-line electro-optical detection of wafer defects.XY translation stage 16 moves wafer 12 in a serpentine pattern beneathan optical imaging system 18. Movement of XY translation stage 16, andtherefore movement of wafer 12, are synchronized, by a central controlsystem 20 via control/data links 22, with action of a multi-componentcamera system in a way that wafer 12 moves the equivalent of one fieldof view 24 during a CCD matrix photo-detector frame time of 33milli-seconds and only a fraction, for example, on the order of about10⁻² of a single pixel during exposure to an illumination system 26,thereby resulting in no image smear or loss of image resolution.

In Step 2, a multi-component electro-optical camera system is provided,including (a) an illumination system 26, (b) an optical imaging system18, (c) an automatic focusing system 7, (d) a focal plane assembly 30,and (e) respective system control/data links, in communication withcentral control system 20.

In sub-step (a) of Step 2, an illumination system 26 is provided,including a repetitively pulsed laser 32, a laser beam expander 34, alaser beam light path 36, and control/data links 38. This type ofillumination system enables ultra fast imaging of a large field of view24, by featuring pulsed laser 32 for repetitively generating andpropagating a highly bright and highly energetic light pulse in anextremely short period of time.

This contributes to the overall method of wafer inspection having highthroughput. Monochromatic laser illumination is also preferably used, inorder to simplify design requirements of the wide field of view opticalimaging system 18, since there are no chromatic aberrations requiringoptical correction or adjustment. Illumination system 26 is incommunication with the central control system 20 via control/data links38.

In system 10, pulse rate, i.e., pulses per second, of pulsed laser 32 issynchronized with frame speed of the array of individual matrixphoto-detectors of focal plane assembly 30. A laser pulse illuminatingfield of view 24 of a wafer die 14, for a time duration of nanosecondscompared to milliseconds frame time of temporally gated camera systemfocal plane assembly 30 of matrix photo-detectors, results ininstantaneous illumination of field of view 24 of an inspected wafer die14. In one very short laser pulse, a relatively large number of pixels,for example, about forty eight million pixels, of focal plane assemblyarray 30 of several, for example, twenty four, matrix photo-detectors,is simultaneously illuminated, and there is essentially no relativemovement among the pixels. The laser light pulse duration issignificantly shorter than the image pixel dwell time, where the pixeldwell time refers to the time a point on the wafer is imaged by adetector pixel while the wafer is moving.

Preferably, repetitively pulsed laser 32 is a Q switched Nd:YAG laser,optically pumped by light emitting diodes, at a pulse rate of 30 pulsesper second, with a pulse time interval of about 10 nanoseconds,generating a pulsed monochromatic light beam at a wavelength of 1.06microns. The pulse rate of pulsed laser illumination system 26 of 30pulses per second, is synchronized with a frame speed of 30 frames persecond, of the array of CCD matrix photo-detectors on focal planeassembly 30.

Optical resolution is a linear function of the illuminating wavelength.Resolution of an optical system increases as illumination wavelengthdecreases. Therefore, to increase resolution of optical system 18 andconsequently defect detection sensitivity of inspection system 10, acrystal 40 having non linear optical properties and serving as a ‘secondharmonic’ generating crystal 40 is placed in laser beam light path 36 ofillumination system 26. Second harmonic generating crystal 40 causeshalving of the wavelength of the laser light beam generated by pulsedlaser 32, for example, from 1.06 microns to 0.53 micron, thereby,doubling resolution of wafer inspection system 10.

In sub-step (b) of Step 2, an optical imaging system 18, is provided,including a focusing lens 42, a beam splitter 44, an objective lens 46,and control/data links 49. This system is suitable for ultra fast highresolution synchronous imaging of high magnification, for example, 50×,of wide field of view 24 of a wafer die 14. An automatic focusing system28 automatically adjusts and sets the position of objective lens 46 ofoptical imaging system 18 for optimum focus of all wafer dies 14 onwafer 12. Optical imaging system 18 is in communication with the centralcontrol system 20 via control/data links 49. During operation of waferinspection system 10, focusing lens 42 images laser light 48, wherelaser light 48 represents light reflected, scattered and diffracted bywafer 12, onto focal plane assembly 30. This imaging process is furtherdescribed with reference to FIG. 5A below.

In sub-step (c) of Step 2, an automatic focusing system 28, includingsensor and control devices (not shown) is provided, which, via opticalimaging system 18, automatically maintains wafer 12, and therefore, awafer die 14, in focus.

In sub-step (d) of Step 2, a focal plane assembly 30 is provided,including a number of detector ensembles 50 (FIGS. 4-5), where eachdetector ensemble 50 features several individual two-dimensional matrixphoto-detectors, preferably but not limited to, at least twotwo-dimensional CCD matrix photo-detectors 52 (FIGS. 3A-3B), focal planeassembly electronics 54, and control/data links 56, 58, and 90, enablinghigh capacity and ultra fast high resolution synchronous imaging of awafer die 14. Preferred structural and configurational components andfeatures of focal plane assembly 30 are provided in FIGS. 3A and 3B,FIGS. 4A through 4D, and FIGS. 5A and 5B, which are schematic diagramsillustrating close-up views of an individual CCD matrix photo-detector52, a detector ensemble 50 and focal plane assembly 30, respectively.

In FIGS. 3A-3B, of schematic diagrams illustrating top and side views ofa two-dimensional CCD matrix photo-detector 52, respectively,photo-sensitive area 60 is surrounded by a photo-insensitive area 62, aconfiguration which prevents the physical placement of two CCD matrixphoto-detectors side-by-side, thus creating a preferably, but notlimited to, continuous, photo-sensitive focal plane. Focal planeassembly 30 (FIGS. 2 and 5A) includes several, for example, six,detector ensembles 50 (FIGS. 4A and 4B), where each detector ensemble 50includes several, for example, four, two-dimensional CCD matrixphoto-detectors 52, for a total of, for example, twenty four,commercially available high resolution, black and white, silicontwo-dimensional CCD matrix photo-detectors 52, wherein each CCD matrixphoto-detector 52 has a very high number of, for example, 1940×1035(i.e., on the order of two million or 2 mega) image sensing pictureelements, or pixels, capable of providing 30 frames per second at highdefinition standards.

Focal plane assembly 30, featuring six detector assemblies 50, eachdetector ensemble featuring an array 64 (FIG. 4D) of four individual CCDmatrix photo-detectors 52, optically couples all twenty-four individualCCD matrix photo-detectors 52 to optically form a, preferably, but notlimited to, continuous, surface of photo-detectors 66 at the focal plane(FIG. 5B), filling the relatively large field of view 24 of the 50×magnification microscopy optical imaging system 18. This opticalconfiguration enables illumination of a wafer die 14 with a single laserpulse and simultaneous imaging by an array 66, of twenty-fourtwo-dimensional CCD matrix photo-detectors, having a total of about 48million (48 mega) pixels. For a CCD matrix photo-detector frame speed of30 frames per second, and an array of about 48 megapixels, imageacquisition of wafer die 14 is at a rate of about 1.5 billion (1.5 giga)pixels per second. Such an image acquisition rate translates to veryhigh system throughput. Focal plane assembly 30 is in communication withcentral control system 20 via control/data links 56 and 58 (FIG. 2).

FIGS. 4A and 4B are schematic diagrams illustrating close-up side viewsof detector ensemble 50, showing geometric configuration of two sets of,for example, two CCD matrix photo-detectors each 52A and 52B.Preferably, each detector ensemble 50 is constructed from two glassprisms 68 and 70, each prism having a right angle and a 45 degreesdiagonal surface. Diagonal surface 72 of prism 68 has zones on which ahighly reflective coating, preferably approaching 100%, are applied. Oneach prism 68 and 70 at least one CCD matrix photo detector is opticallybonded. Exemplary set of two CCD matrix photo-detectors 52A bonded onprism 68 is identical to exemplary set of two CCD matrix photo-detectors52B bonded on prism 70. In FIG. 4B, the set of two CCD matrixphoto-detectors 52A are shown bonded in straight file on prism 68, andthe set of two CCD matrix photo-detectors 52B are bonded in straightfile on prism 70, and the exact position of the bonded CCD matrixphoto-detectors is selected such that all photo-sensitive areas 60 ofindividual CCD matrix photo-detectors 52A and 52B optically appear asone continuous straight strip when viewed from View A.

FIG. 4C is a schematic diagram illustrating a close-up view of diagonalsurface 72, of glass prism 68, including zones of highly reflectivecoating. FIG. 4C shows a view of Section B—B of FIG. 4A, wherein zones74, on diagonal surface 72, are coated with highly reflective coating,and are arranged on surface 72 to be opposite photo-sensitive areas 60of CCD matrix photo detectors 52A bonded on prism 68. Light enteringdetector ensemble 50 along View A, opposite reflective zones 74, arereflected by reflective zones 74 and deviated by 90 degrees to impingeupon CCD matrix photo-detectors 52A. Light entering detector ensemble 50along View A, not opposite reflective zones 74 pass through prisms 68and 70 undeviated and impinge upon CCD matrix photo-detectors 52B.

FIG. 4D is a schematic diagram illustrating a close-up front opticalview, of detector ensemble 50 shown in FIGS. 4A-4C, showing theappearance of an optically continuous surface of photo-detectors,featuring the plurality of CCD matrix photo detectors 52. FIG. 4D showsView A of FIG. 4B and demonstrates the creation by optical means ofcontinuous surface 64, featuring four photo-sensitive photo-detectorareas 60. Within surface 64, those photo-sensitive areas 60 oppositereflecting zones 74 are associated with CCD matrix photo-detectors 52Abonded onto prism 68. The other photo-sensitive areas 60 not oppositereflecting zones 74 are associated with CCD matrix photo-detectors 52B,bonded onto prism 70. Photo-detectors 52A and 52B are in differentsurfaces or planes and photosensitive areas 60 are not continuous, butdetector ensemble 50 creates surface 64 by optical means.

FIG. 5A is a schematic diagram illustrating a close-up view of focalplane assembly 30, including beam splitting prisms 76 and 78, anddetector ensembles 50. In FIG. 5A, focal plane assembly 30 includes sixdetector ensembles 50, two labeled 50A, two labeled 50B, and two labeled50C. Light 48, representing reflected, scattered, and diffracted laserillumination light coming off of wafer 12, is directed and focused intofocal plane assembly 30 by focusing lens 42. Light 48 passes throughbeam splitting glass cube 76 which reflects, at 90 degrees,approximately 33% of light 48, forming imaging channel 80, and transmitsabout 67% of light 48. Transmitted light 82 emerging from beam splittingcube 76, goes through a second beam splitting cube 78 which reflects, at90 degrees, approximately 50% of light 82, forming imaging channel 84,and transmits about 50% of light 82, forming imaging channel 86.

This configuration of the combination of beam splitting cubes 76 and 78creates three imaging channels 80, 86 and 84, each with equal lightenergy, and each with approximately 33% of the light energy of originalinput light beam 48. Optical cube 83 is inserted in imaging channel 80so as to equalize the amount of glass in the optical paths of all threeimaging channels, thus enabling similar image quality formed in allthree channels. At the focus point of focusing lens 42, for each of thethree imaging channels 80, 86, and 84, two sets of detector ensembles 50are placed. One set of two detector ensembles 50A is placed in imagingchannel 80, one set of two detector ensembles 50B is placed in imagingchannel 86, and one set of two detector ensembles 50C is placed inimaging channel 84.

FIG. 5B is a schematic diagram illustrating front optical View A offocal plane assembly 30 demonstrating optical formation of continuoussurface 66 of photo-detectors at the focal plane, by using six detectorensembles 50 and twenty-four two-dimensional CCD matrix photo-detectors52 located in different geometrical surfaces.

In (e) of Step 2, referring again to FIG. 2, control/data links,including 38, 49, 54, 56, and 58, and central control system 20, featureelectronic interconnections among the different systems and systemcomponents, enabling proper automation and synchronization of thevarious steps of the method of detection of wafer defects. For example,automatic movement of wafer 12 via movement of XY translation stage 16is electronically set at a linear speed such that wafer 12 moves adistance of one field of view 24 between the time of two pulses emittedby pulsed laser 32 in illumination system 26. Temporally gated openingand closing, or frame speed, of focal plane assembly 30, including allCCD matrix photo-detectors 52 is synchronized with the pulse rate ofpulsed laser 32 in illumination system 26.

In Step 3, the camera system of Step 2 is adjusted, focused, and set toa position over an inspected field of view 24 within a wafer die 14, viacentral control system 20 signals. Pulse rate of pulsed laser 32 inillumination system 26 is synchronized with the frame speed of CCDmatrix photo-detectors 52 included in detector ensembles 50A, 50B, and50C of focal plane assembly 30. This step is performed in order toenable movement of wafer 12, and therefore, of an inspected wafer die14, at a speed such that an inspected field of view 24 is covered duringthe time interval of one frame of CCD matrix photo-detectors 52 of focalplane assembly 30.

In Step 4, instantaneous illumination of an inspected field of view 24of an inspected wafer die 14 of Step 3 is achieved by generating a laserpulse onto inspected wafer die 14, for a time duration, for example, tennanoseconds, orders of magnitude less than synchronized pulse rate andframe time of camera system CCD matrix photo-detectors 52, via a centralcontrol system 20 signal. In a ten nanosecond laser pulse, about 48million pixels, of focal plane assembly 30 featuring twenty-four CCDmatrix photo-detectors 52, is simultaneously illuminated, and there isno relative movement among the pixels. During the short laser pulse,there is effectively no wafer motion during the wafer exposure time,since the laser pulse duration is much shorter than the pixel dwelltime, which is the time a point on the wafer is imaged by a detectorpixel while the wafer moves, and therefore, there is effectively noimage smear degrading image resolution, as is typically the case inwafer inspection methods and systems featuring continuous illuminationof a wafer.

In Step 5, illuminated inspected field of view 24 of Step 4 is imaged byoptical imaging system 18 onto focal plane assembly 30, optically linkedto detector ensembles 50A, 50B, and 50C, featuring the twenty-four, twodimensional CCD matrix photo-detectors 52, via central control system 20signal.

In Step 6, the digital image (not shown) of Step 5, featuring about 58million pixels, of an inspected field of view 24 of a wafer die 14 isacquired by using focal plane assembly 30 optically forming a,preferably, but not limited to, continuous surface of at least twotwo-dimensional CCD matrix photo-detectors 52, by synchronized openingof temporally gated CCD matrix photo-detectors 52, via a central controlsystem 20 signal. During the frame time interval of each activated CCDmatrix photo-detector 52, wafer 12, and therefore, wafer die 14, movesvia XY translation stage 16 the equivalent of one field of view. Thiscorresponds to a large pixel dwell time relative to laser pulse timeinterval, resulting in the wafer moving only a fraction, for example, onthe order of 10⁻², of a single pixel during exposure to array 66 (FIG.5B) of CCD matrix photo-detectors 52 of focal plane assembly 30, therebypreventing image smear or loss of image resolution. In sub-step (a),acquired digital image data is grabbed via a set of parallel configuredimage processing channels 90 by an image grabber 92, and is saved in animage memory buffer 94, part of image processing system 100 (FIG. 2).

In Step 7, Step 3 through Step 6 are sequentially repeated for imageacquisition of the next fields of view within the same inspected waferdie 14, thereby forming a strip of fields of views until and includingthe first equivalent field of view of the nearest neighboring wafer diein the strip, serving as a reference. This automated sequential imagingprocess is clearly illustrated in FIG. 6, which is a schematic diagramillustrating a close-up view of the image acquisition process featuringwafer dies, where each wafer die is sequentially inspected by imaging aplurality or strips of fields of view, one field of view at a time. InFIG. 6, following image acquisition of first field of view 24A in firstinspected wafer die 6A, there is image acquisition of 0.0 second fieldof view 24B in same first inspected wafer die 14A. Synchronized withserpentine motion of wafer 12, image acquisition of successive fields ofview, one after another, progresses throughout entire first inspectedwafer die 14A, and continues until an image is acquired for first fieldof view 24J in second inspected wafer die 14B. This process results inthe formation of continuous strips 110 of imaged wafer dies 14, untileventually entire wafer 12 is completely imaged.

In Step 8, digital image data of each field of view in an inspectedwafer die and, of each equivalently located field of view in the nearestneighboring wafer die, serving as a reference, are processed, by usingan image processing system. Referring to FIG. 2, image processing system100 includes parallel configured image processing channels 90 for imagegrabbing by an image grabber 92, an image buffer 94, a defect detectionunit 96, a defect file 98, and control/data links 102. Image dataacquired by focal plane assembly 30 featuring twenty-fourtwo-dimensional CCD matrix photo-detectors 52 is processed in parallel,whereby each of the twenty-four CCD matrix photo-detectors 52communicates separately, in parallel to the other CCD matrixphoto-detectors 52 of focal plane assembly 30, with image grabber 92,via twenty-four separate image processing channels 90. Instead ofprocessing image data using a single serial channel of 48 megapixels ata CCD frame speed acquisition rate of 30 times per second, resulting ina single channel with a very high, 1.5 gigapixels per second processingrate, each of the twenty-four separate image processing channels 90having about 2 megapixels of image data, acquired at a rate of 30 timesper second, is used for processing at a moderate rate of 60 megapixelsper second. In this configuration, an overall image processing rate of1.5 gigapixels per second is achieved using significantly slowerindividual channels, which are easier to implement in wafer defectdetection system 10 using commercially available hardware. This featureof parallel processing of acquired image data contributes significantlyto the resulting high throughput of the method of wafer inspection ofthe present invention. Image processing system 100 is in communicationwith central control system 20 via control/data links 102.

Step 8 includes sub-step (a) performing an image alignment between theinspected field of view and the reference field of view, sub-step (b)identifying the presence of a potential wafer defect, sub-step (c)saving the comparison data in a defect file, and sub-step (d) deletingunneeded image data of the first field of view of the first inspectedwafer die.

In sub-step (a) of Step 8, an image alignment is performed between theimage of each inspected field of view and the corresponding field ofview serving as a reference, prior to identifying the presence of apotential wafer defect in the inspected wafer die. Due to minormechanical inaccuracies during movement of XY translation stage 16,velocity of a wafer 12 beneath camera optical imaging system 18 is notconstant. As a result of this, image pixel positions in the multiplefields of the CCD matrix detectors may not be as initially programmedaccording to inter-system synchronization. Therefore, a two-dimensionaltranslational image alignment correction between an inspected field ofview and a reference field of view is performed. More complex rotationregistration correction may also be performed, but for standardimplementation of the method and system of the present invention, it isneglected. This process of aligning images of fields of views, prior todefect detection by image comparison is illustrated in FIG. 6 forexemplary strips 110 of equivalent fields of view. Pixel positions inthe image of first field of view 24A of first inspected wafer die 14Aand pixel positions in the image of equivalently located first field ofview 24J of nearest neighboring wafer die 14B are extracted from imagebuffer 94, and are subjected to an image alignment correction. In thisprocess, first field of view 24J of nearest neighboring wafer die 14Bserves as the reference to equivalent field of view 24A of firstinspected wafer die 14A.

Prior art methods and systems of wafer defect detection, such as thosedescribed above, featuring a combination of continuous waferillumination and acquiring a two dimensional image by either scanning awafer in one or two dimensions, require a registration correction forall pixels or all pixel lines. This limits overall system speed, i.e.,throughput, and increases requirements of electronic hardware andoverall system costs. Moreover, this results in residualmisregistration, since no correction procedure is accurate for allpixels in an image. Residual misregistration significantly reducessystem defect detection sensitivity. In contrast, for the preferredembodiments of the method and system of the present invention, all focalplane assembly CCD matrix detector pixels in any given field of view ofthe focal plane assembly are considered one unit, and are generatedsimultaneously by a single laser pulse. Therefore, there is no need forpixel registration within a focal plane assembly field of view, and asimple alignment correction between any small localized zone within theinspected field of view and the equivalent zone in a reference field ofview is correct over the entire focal plane assembly field of views.Therefore, in the present invention, residual misregistration isnegligible, enabling improved defect detection sensitivity.

In sub-step (b) of Step 8, following image alignment correction, thereis identification of the presence of a potential wafer defect in theinspected wafer die, by comparing differences of pixel intensities ofthe image of each, starting from the first, field of view of theinspected wafer die to pixel intensities of the image of eachequivalently located, starting from the first, field of view of thenearest neighboring wafer die. In this defect identification step, astandard algorithm of defect detection is used, which is based on theanalysis of comparing pixel intensities of images acquired fromidentical fields of view of adjacent neighboring wafer dies, featuring alike pattern. Defect detection is based on a statistical approach,whereby the probability that a defect will exist at the equivalentlocation within adjacent wafer dies is very low. An exemplary standardalgorithm for locating irregularities among pixel intensities ofdifferent images is based on a three-die comparison. The overall waferinspection system is programmed to inspect the pattern, pixel-by-pixel,of a wafer die or field of view, typically referred to as the inspectedpattern, and then compares it to the supposedly equivalent pattern ofthe adjacent neighboring wafer die on the same wafer, which serves as areference. A defect detector detects any pattern irregularity ordifference which would indicate the possible presence of a wafer defectin the current inspected wafer die. The pattern under test is alsocompared with the equivalently located pattern of another adjacent waferdie in order to resolve ambiguity that may exist if the test pattern wascompared with only a single pattern. In the second comparison, in orderto maintain symmetry, the pattern under test serves as the reference.

This image comparison process, performed by defect detection unit 96(FIG. 2) is illustrated in FIG. 6. Each pixel intensity in the image offirst field of view 24A of first inspected wafer die 14A is compared tothe pixel intensity in the image of equivalently located first field ofview 24J of adjacent neighboring wafer die 14B.

In sub-step (c), according to pre-determined comparison criteria, suchas a specified difference or irregularity threshold level, a differenceor irregularity in intensity of the two corresponding pixels inequivalently located first fields of view 24A, and 24J, of wafer dies14A, and 14B acting as a reference, respectively, is saved in waferdefect file 98, in order to be further processed by a decision stepconfirming or dismissing defect existence and location (Step 10).

In sub-step (d), unneeded image data of first field of view 24A of firstinspected wafer die 14A is deleted from image buffer 94. As data of thecomparison of equivalently located first fields of view 24A and 24J offirst inspected and second inspected wafer dies 14A and 14Brespectively, is saved, image data of first field of view 24A of firstinspected wafer die 14A is no longer needed for image processing ofsuccessive wafer dies 14 in wafer 12.

In Step 9, Step 7 and Step 8 are repeated for sequential fields of viewin second inspected wafer die 14B, until and including processing theimage of first field of view 24N of third inspected wafer die 14C. Steps7 and 8 are carried out in parallel. While image acquisition in Step 7is carried out for each field of view in a strip 110, image processingand comparison of each preceding field of view in a strip 110 is carriedout according to Step 8.

Step 10 is a decision and confirmation step, performed by defectdetector unit 96, deciding and confirming whether or not there isdetection of a wafer defect in each field of view, starting with fieldof view 24J of wafer die 14B, initially processed according to Step 8.Presence of irregularity or difference between equivalently locatedfirst fields of view 24A and 24J of first and second wafer dies 14A and14B respectively, is followed by the next comparison betweenequivalently located first fields of view 24J and 24N of second andthird wafer dies 14B and 14C, respectively, in order to confirm ordismiss the presence of a defect located in field of view 24J of waferdie 14B.

In sub-step (a) of Step 10, confirmed wafer defect information,including location of the confirmed wafer defect, is appropriately savedin defect file 98 for possible use in feedback control of a waferfabrication process.

In Step 11, Step 7 through Step 10 are repeated, sequentially, forinspection of each field of view in a field of view strip 110 within thesame wafer. In FIG. 6, for example, wafer field of view 24K in wafer die14B becomes the next inspected field of view to be subjected to imageprocessing by Step 7 through Step 10. Starting with field of view 24K inwafer die 14B, images of successive fields of view in second wafer die14B are to be compared to equivalently located images of fields of viewin wafer dies 14A and 14C. Field of view 24K in wafer die 14B iscompared to equivalently located field of view 24B in wafer die 14A,with field of view 24B serving as the reference, and field of view 24Kin wafer die 14B is compared to field of view 24P in wafer die 14C, withfield of view 24K serving as a reference. In this case, each image ofeach successive set of fields of view in a strip 110 is compared once toan equivalent field of view on a wafer die proceeding it in the stripand once compared to an equivalent field of view on a wafer diesucceeding it in the strip. Each compared field of view serves once as areference field of view in the comparison and once as an inspected fieldof view in the comparison. Synchronized with serpentine motion of wafer12, selection, illumination, imaging, acquisition, and processing, of animage of successive fields of view of successive wafer dies, one afteranother, progresses from wafer die to wafer die throughout entire wafer12, until all wafer dies 14 of wafer 12 are inspected for defects.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

What is claimed is:
 1. A method for electro-optically inspecting apatterned semiconductor wafer of dies for a defect, the methodcomprising: providing a repetitively pulsed laser illuminating source;illuminating at least one field of view in each of a plurality of waferdies using said pulsed laser illuminating source; acquiring images ofsaid at least one field of view in each of said plurality of wafer dies;and detecting a wafer defect by comparing said images using a die-to-diecomparison method.
 2. An inspection method according to claim 1, andwherein said detecting includes parallel processing of multiple portionsof said images.
 3. An inspection method according to claim 2, andwherein: said at least one field of view comprises multiple fields ofview; and said multiple portions of said image correspond to saidmultiple fields of view.
 4. A system for electro-optically inspecting apatterned semiconductor wafer of dies for a defect comprising: arepetitively pulsed laser illuminating source, illuminating at least onefield of view in each of a plurality of wafer dies; a camera, acquiringimages of said at least one field of view in each of said plurality ofwafer dies; and a wafer defect detector, detecting a wafer defect bycomparing said images using a die-to-die comparison method.
 5. Anelectro-optical device for inspecting a patterned semiconductor wafercontaining dies for a defect comprising: a focal plane assemblyincluding at least one detector ensemble including an array of at leasttwo two-dimensional matrix photo-detectors operating with a mechanismfor simultaneous acquisition of images of each of at least oneilluminated field of view in each of a plurality of dies.
 6. A deviceaccording to claim 5, wherein said at least one illuminated field ofview comprises a plurality of illuminated fields of view.
 7. Aninspection method according to claim 1, and also comprising moving thepatterned wafer along an inspection path.
 8. An inspection methodaccording to claim 1, wherein said illuminating comprises sequentiallyilluminating at least one field of view in each of the plurality ofwafer dies using said pulsed laser illuminating source.
 9. An inspectionmethod according to claim 1, wherein said illuminating comprisesilluminating each of a plurality of fields of view in each of theplurality of wafer dies using said pulsed laser illuminating source. 10.An inspection method according to claim 9, wherein said illuminatingcomprises sequentially illuminating each of the plurality of fields ofview in each of the plurality of wafer dies using said pulsed laserilluminating source.
 11. An inspection method according to claim 1,wherein said acquiring comprises sequentially acquiring images of saidat least one field of view in each of said plurality of wafer dies. 12.An inspection method according to claim 1, wherein said acquiring stepis performed using an electro-optical camera including at least twotwo-dimensional matrix photo-detectors simultaneously acquiring imagesof each of said plurality of said sequentially illuminated fields ofview in each of a plurality of the wafer dies.
 13. An inspection methodaccording to claim 1, and wherein said repetitively pulsed laserilluminating source is a Q switched Nd:YAG laser.
 14. An inspectionmethod according to claim 13, and wherein said Q switched Nd:YAG laseris optically pumped by light emitting diodes.
 15. An inspection methodaccording to claim 12, and wherein said electro-optical camera furtherincludes a non-linear optical crystal functioning as a second harmonicgenerating crystal, placed in a laser beam light path of saidrepetitively pulsed laser illuminating source, said non-linear opticalcrystal halving wavelengths of said laser beam light generating by saidrepetitively pulsed laser.
 16. An inspection method according to claim12, and wherein said electro-optical camera further includes a focalplane assembly including at least one detector ensemble including anarray of said at least two two-dimensional matrix photo-detectors, eachof which comprises a high resolution, back and white two-dimensionalmatrix photo-detector.
 17. An inspection method according to claim 12,and wherein each of said at least two two-dimensional matrixphoto-detectors comprises a two-dimensional CCD matrix photo-detector.18. An inspection method according to claim 16, and wherein said focalplane assembly optically forms a surface of said at least twotwo-dimensional matrix photo-detectors at a focal plane within saidelectro-optical camera.
 19. An inspection system according to claim 4,and wherein said repetitively pulsed laser illuminating source comprisesa Q switched Nd:YAG laser.
 20. An inspection system according to claim19, and wherein said Q switched Nd:YAG laser is optically pumped bylight emitting diodes.
 21. An inspection system according to claim 4,wherein said camera comprises an electro-optical camera including atleast two two-dimensional matrix photo-detectors simultaneouslyacquiring images of each of said plurality of said sequentiallyilluminated fields of view in each of a plurality of the wafer dies. 22.An inspection system according to claim 21, and wherein saidelectro-optical camera further includes a focal plane assembly includinga least one detector ensemble including an array of said at least twotwo-dimensional matrix photo-detectors, each of which comprises a highresolution, black and white two-dimensional matrix photo-detector. 23.An inspection system according to claim 21, and wherein each of said atleast two two-dimensional matrix photo-detectors comprises atwo-dimensional CCD matrix photo-detector.
 24. An inspection systemaccording to claim 22, and wherein said focal plane assembly opticallyforms a surface of said photo-detectors at a focal plane within saidelectro-optical camera.
 25. An electro-optical device according to claim5, and wherein each of said at least two two-dimensional matrixphoto-detectors comprises a two-dimensional CCD matrix photo-detector.26. An electro-optical device according to claim 5, and wherein saidfocal plane assembly optically forms a surface of said at least twotwo-dimensional matrix photo-detectors at a focal plane within saidelectro-optical device.
 27. An inspection system according to claim 21,and wherein said electro-optical camera further includes a non-linearoptical crystal functioning as a second harmonic generating crystal,placed in a laser beam light path of said repetitively pulsed laserilluminating source, said non-linear optical crystal halving wavelengthsof said laser beam light generated by said repetitively pulsed laser.28. A method for electro-optically inspecting a patterned semiconductorwafer containing dies for a defect, comprising: providing a focal planeassembly including at least one detector ensemble including an array ofat least two two-dimensional matrix photo-detector; and simultaneouslyacquiring images of each of at least one illuminating field of view ineach of a plurality of dies.